This invention relates to wire connectors of the insulation displacement type. While the connector of the present invention can be used to connect wires in a wide range of applications, it is particularly suited for connecting a replacement ballast in a fluorescent light fixture. Electricians replacing a ballast in a fluorescent light fixture generally find it most efficient to remove the electrical connections to the old ballast by simply cutting the wires to the ballast. After mounting the new ballast in the fixture a fast, easy way to make a reliable electrical connection is needed. Insulation displacement connectors (IDC) can be used to save the time otherwise needed for stripping the insulation from the ends of the newly-cut wires. An IDC has a conductive contact element, referred to herein as a clip, that cuts through the insulation of two or more wires to be connected. The clip is thus placed in direct contact with the underlying conductors, providing electrical continuity between the conductors. Examples of this type of connector are shown in U.S. Pat. Nos. 4,461,528 and 3,845,236.
For an IDC to make reliable connections, it must have a way to pierce the wire insulation and drive its clip into direct contact with the underlying conductors. This can be a difficult task, especially with some types of tougher insulation such as nylon on top of PVC. The clip may be provided with sharpened knife edges to facilitate penetration of the insulation but the knife edges are difficult to form and therefore significantly increase the manufacturing cost of the connector. Another approach to making reliable electrical contact is to use a dual engagement clip. Such a clip has a base with two aligned sets of fingers or tines engaging each wire being connected. This increases the holding or gripping ability of the connector and doubles the opportunity to make a solid electrical connection. While a dual engagement clip increases the force required to cut through the insulation, various forms of pliers can easily supply the required force. However, the closure forces developed by pliers can wreak havoc on the plastic housings normally supplied with IDC connectors. To avoid this problem prior IDC connectors either close by hand without tools (U.S. Pat. No. 4,461528 or locate the clip external to the housing (U.S. Pat. No. 3,845,236) where it engages the pliers directly. After the clip is driven home by the pliers, a portion of the housing must be wrapped around the exposed clip to insulate it. The resulting two-step process takes longer to complete than a connector that can be closed in one step.